Simulation of solar energetic particle event onset time associated with coronal mass ejections

摘要:

通过两种不同方法对太阳高能粒子(Solar Energetic Particles,SEP)通量初始时刻进行研究,一种是数值模拟方法,即数值模拟中取第一颗粒子出现的时刻来确定,另一种是观测背景方法,即通过太阳高能粒子通量随时间变化的背景值与上升值的拐点时刻来确定.Kahler(2013)定义的SEP时间尺度TO(the onset time from CME launch to SEP onset,从CME爆发时刻到SEP初始时刻的时间段)、TR(the rise time from onset to half the peak intensity(0.5Ip),从SEP初始时刻的上升时间直到半峰值时刻)、TD(the duration of the SEP intensity above 0.5Ip,SEP强度高于半峰值的持续时间)都与SEP通量初始时刻相关.将CME驱动激波作为源,利用粒子输运方程,对SEP传播进行数值模拟.然后对描述SEP时间尺度的TR、TO的数值模拟值与观测进行对比,发现两者吻合很好,即TR随CME速度和宽度增加而增加.由于TO影响的因素较为复杂,并没有很好的规律性.另外,当源位置经度距离观测者较远的时候,影响时间尺度TR,TO的因素较多.因此,用不同方法确定的SEP通量初始时刻对TR,TO的影响不大;当源位置经度距离观测者较近的时候,观测背景方法下的数值模拟与观测更加符合.

We study the onset time of SEP flux with two different methods.The one is a simulation method,which suggested the onset time is when a first particle is detected by the observer.The other one is the observation background method,which proposed the onset time is determined by the inflection point between the background and the rise on the SEP flux time profile.The SEP timescales TO and TR defined by S.W.Kahler shown in the last paragraph are associated with the SEP onset time.In this work,we solve the transport equation for SEPs considering ICME shocks as energetic particle sources.We obtain the SEP timescales TR,TO with the two method by simulating the SEP transport.The simulation results which are consistent with the observation,suggested that TR increase with the increasing CME speed and width,and TO is not presented a good regularity with complexed factors.Moreover,when the source location longitude is far away from the observer,as so many factors affecting timescales TR and TO,the different SEP onset time method has little effect on the results.When the source location is close to the observer,the simulation results with the observation background method is more consistent with the observation conclusion.

作者:

秦刚 祁诗阳

Qin Gang;Qi Shiyang(National Space Science Center,Chinese Academy of Science,Beijing 100190,China;College of Earth Sciences,University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区:

中国科学院国家空间科学中心 中国科学院大学地球科学学院

出处:

《betway官方app 学报：自然科学版》 CAS 北大核心 2019年第1期1-10,共10页

基金:

国家自然科学基金(NNSFC 41574172)

关键词:

太阳高能粒子 日冕物质抛射 数值模拟 行星际输运

solar energetic particle coronal mass ejections numerical simulation interplanetary transport

分类号:

P353 [天文地球—空间物理学]

与日冕物质抛射相关的太阳高能粒子事件初始时间的数值模拟研究.pdf